Telephone system



Dec. 1 l925- J. B. NEWSOM TELEPHONE SYSTEM Filed Dec. 15, 1923 /f7l/e/zf0/z' James 5 /I/ewsam,

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Patented Dec. l, 1925..

*UNITED 'STATES PATENT OFFICE.

JAMES E. NEWSOM, OE BROOKLYN, NEW YORK, AsSrGNOR To WESTERN ELECTRIC COMPANY, INCORPORATED, OENEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

iApfilzcation'led December 15,1923. 'Serial No. 680,808.

To all whom t 1mg-concern.'

Be it known that I, kJAMES B. NEwso-M, a citizen of the United States of America, residing at Brooklyn, in the county of Kings, State yof New York, have linvented certain new and usefullfmprovements in Telephone Systems, 'of `which the following is a full, clear, concise, and exact description.

This invention relates `to telephone systems, and more particularly, to improvements inthe impulse sending circuits used in restablishing connections between manual and automatic exchanges.

This invention is adapted for use in systems in whichtelephone lines terminating at a private lbranch exchange switchboard mgay be extended by means of operators link circuits ythrough trunk circuits and automatic switches to telephone lines terminating in an automatic exchange. private branch exchange operator is pro- Avided with an impulse senderthat may be associated with a link circuit and operated to `transmit impulses to Iselect the desired line. The control-ofthe switches'is'elfected by the aid of an impedance element bridge acrossthe talking conductors of the link and trunk vcircuits 4the moment the impulse sender `is associated therewith, and this im;- petlance lelement fis short circuited during the transmissionofimpulses.

.'An object of this invention is to fprovi'de an improved system of this ycharacter' by means of whichithe introduction ofthe impedance `'element across the talking conductors lwill not disturbthe control of thel automatic switches. i

Anotherobject offthe'invention is to :maintain the-impulse contacts of the-'sender shortcircuited while the sender isin 'non-operated position 'and connected to thelin-k circuit.

To attain-these objectsin accordance with one "feature .of this invention, a relay arrangement :is `provided wherebya resistance is n'omentarily introduced nin parallel rwith the impedance Velement when `,bridged :across the cond'uctorsto reducethe inductive effect on theimpulserespo'nsive relays'lused in cir-1 cuits of this type for contro-lling the operation ofV the "automatic switches. r y

AAffurther feature is the provision ofua relay arrangement `whereby a short-circuit 'of the in'ipulsecontacts andltheiimpedance element are both removed from across the 'talk- In such systems the ing conductors when the impulse sender is actuated.

For a miore `complete understanding of this invention, referenceshould lbe made to the following description and the accompanying drawing` in which Fig. l illustrates one embodiment of the -invention as applied to a private branch exchange system. Fig.

A2 shows-a diagrammatic 1form the'inclusion 'also shown diagrammatically, for effecting connections between the trunk -Oircuit and telephone lines such as E terminatingat the automatic' exchange.

The nature of the invention is -suchtha't-a clear understanding will be obtained from a description of the invention as-shown in the drawing While tracing a callffromthe cal'ling subscriber on lline A tov-the fwantedgsubscriber on line E, and it will be sodescribed.

Assuming that the subscriber on line A has initiated a call `andfthe answering lfend. l

of 'the link circuitB associated therewith in any well-known nianneiyjtlie-operator actuates the listening and dialing -key fconnecting her telephone -se't in circuits as .follows: battery, lower right-hand 'windingof repeating coil 2, lowery operated contacts of key-5, through` the operator?s ytelephone Yset 1;(notsho'wn infdetail), left-hand armaturey and back contactof relay 20, inner upper actuated contacts offkey 5, upper vright-:hand windingo'f induction coil 2-to .ground. The operator mayfno-vv'converse with the calling subscriber through vrepeating coil 2 .and

line A to ascertain .the lnumberofthe 'line with 'which connection isdesired. Assumping'that connection is desired iwithithe -station on lin-e E terminatinglat automaticexchange D, ithe operator inserts calli-'n'g'plug 6 `ofthe link circuit B Vinto :jack 17 Vof'trunk circuit C `and thereby causescircuit connections to Ibemade as is well known 'in the art to connect an impulse responsive relay such as 10 directly through the talking conductors oi the link circuit to battery at repeating coil 2. The circuit for relayV 10 may be traced as Jfollows: battery, right-hand winding of relay 10, tip contacts of jack 7 and plug 6, upper make-before-break contact of relay 12, upper right-hand winding of induction coil 2 to ground, and a similar circuit from battery, lower right-hand winding of induction coil 2, lower make-betore-break contacts of relay 12, ring contacts oi' plug 6 and jack 7, left-hand winding ot relay 10 to ground. These circuits operate the impulse responsive relay 10 which thereby prepares the circuit ot the selector switch tor the reception of impulses from the impulse sender 15, over a circuit hereinafter to be traced.

The operation ofthe sender 15 to effect a connection with the subscribers line E will now be described. The sender 15 may be ot' any well-known construction provided with impulse ycontacts 16 and olinormal Contact 17; When the operator moves the sender from normal an energizing circuit for relayY 2O is completed as follows: battery, winding of relay 20, olif-normal contact 17 to ground. Relay 20, in operating, disconnects the operators telephone set 1 from the talking connection to the calling subscriber, at its left-hand armature and back contact and at its outer right-hand4 armature and front contact closes a circuit including the resistance 21 in parallel with a high impedance element or retardation coil 22 into a circuit hereinafter to be describedrfor holding the impulses responsive relay 10 in operated position. The connection of contact 17`to ground also completes an energizing circuit Jfor relay 12 as tot lows: battery, winding' of relay 12, Yupper actuated contacts of key 5, make-beforebreak contacts of relay 19', olii-normal contact 17 to ground. The operation ot relay 12 closes a circuit for relay 19 as follows: battery, winding otl relay 19, lower outer armature and front contact of relay 12 to ground. Relay 19,' in operating,closes a locking circuit ttor relay 12 as follows: battery, winding of relay 12, upper actuated contacter key 5, a make-before-break contact and armature of relay 19 to ground. The operation of relays20 and 12 closes a circuit for slow-torelease relay 23 'as tollows': battery, winding of relay 23, inner right hand armature andtront contact of relay 20, lower outer armature and front contact of relay 12 to ground. It should be noted here that the operation of relay 12 which occurs slightly after the operation of relay`20 also breaks the circuit for relay 10 through the repeating coil 2 and completes the holding circuit 'for relay `10 in conjunction with contacts of relays 23 and 20. This circuit may be traced as follows: battery, rightfhand winding of relay 10, tip contacts of jack 7 and plug 6, a make-beltore-break contact and upper armature of relay 12, retardation coil 22 and resistance 21 in parn allel, the closed outer right-hand armature and front contact of relay 20 and lett-hand armature and front contact ot relay 23, impulse contacts 16 and make-betore-bi'eak contacts of relay 211 in parallel, lower inner armature and front contact ot relay 12, ring contacts of plug 6 and jack 7, left-hand winding ot relay 10 to ground. It should be noted that this circuit, due to the tact that retardation coil 22 and resistance 21 are in parallel, prevents relay 1() from decliergizing as current through these elements builds up suiciently tast to hold relay 10 energized and thus the breaking of the direct connection to battery at repeating coil 2 will have no effect on the relay 10. The operation of relay 23 also completed an energizing circuit :tor relay 2-1 as follows: battery, winding of relay 211, right-hand armature and front contact of relay 23,` oit-normal contact 17 to ground. The operation of relay 24 removes at its make-beore-break contacts the short circuit for the impulse contacts 16 and at its armature short circuits the resistance 21 and retardation coil 22 and extends Y the impulse circuit for relay 10 directly under control ot the impulse contacts 16. Relay 24 is made slow to operate so that the short circuit for the impulse contact- 16 will not be removed until the operator actually is ready to start the selecting operations and any slight disturbance of the impulse sender while the conversation between the subscriber and the operator takes place will not have any effect on the impulse circuit for relay 10. On return of the sender to normal the circuit for the impulse responsive relay 10 is interrupted a number of times equal to the first digit of the number desired and the selector switch is accordingly set in the usual manner wellknown in the art of automatic telephony and the second series of impulses will, in a similar manner, operate the connector to extend the connection to the wanted subscriberv on line E.'

It is, of course, necessary to maintain relay 10 operated during the intervals between series of impulses, after the sender operations are completed and while the dialing key is still operated. rlhis is accomplished by including the retardation coil 22 in a shunt across the talking conductors, that is, at the moment the sender is returned to normal direct connection for relay 10 is broken and the retardation coil 22 inserted in its place. This might ordinarily, due to the high impedance of this coil, cause a release of the relay 10. In order to prevent this, a temporary path through the resistance 21 `in parallel with the coil 22 is provided so that the current through the coil will have time to build :up suflioiently to hold relay l when resistance 21.is later removed. rIhe lfunctions of the relays for accomplishing this purpose will now be described.

At. the rreturn of the impulse sender to normal the ground lat oft-normal contact 17 is removedcausing relays 20 `and 24E to release. Relay 24, in releasing, removes the direct connection for relay 10 tothe impulse contact- 1G and short-circuits these contacts as previously described and also includes the retardation coil 22 and resistance 21 in parallel in a bridgeacross the conductors over the following circuit: battery, right-hand winding of relay 10, tip contacts of jack 7 and plug 6, an upper make-before-break contact and `armature of relay 112, retardation coil 22 and resistance 21 in parallel, left-hand armature and front contact of relay 23, make-beforebreak contacts of relay 24- and impulse contacts 16 in parallel, lower inner armature .and a make-before-break contact of relay 12, tip contacts of plug 6 and jack 7, left-hand winding of relay 10 to ground. This circuit, therefore, provides `a low resistancepath for the current for relay 10 so that it will not be released, but receive at once suflicient current to prevent `it from being inany way effectedby the changeover. However, this path is merely temporarily maintained as relay 2O in releasing breaks at its inner right-hand armature and front contact the circuit forrelay 23 and at its outer right-hand armature and front contacts breaks one connection for resistance 21. lVhen relay 23 releases the other connection for resistance 21 is opened at the left-hand armature and front contact of this relay so that now only the retardation coil 22 is bridged across the conductors tomaintain relay 10 energized. At this time, however, due to theslow release of relay 23, the circuit through retardation coil 22 has been suf- Vliciently built up to hold relay 10 energized;

It should be noted that relays 19 and 12 arestill maintained energized and will not releaseuntilthe dialing key 5 is returnedto normal. When -the'dialing operations are completed the Voperator releases-key 5 and all relaysrincluding relays 12 and 19 are released. Therele'ase of relay 12 causes the,

circuit for relay l:10 to be removed from the path through'the retardation coil-22 vand eX- tended as previouslytraced through the talkingconductors to battery at repeating coil 2.' The release of key 5 thus removes the impulse sender 115, the operators telephone set 11 and the associated relay arrangement from thelink circuit. The impulse-sender may then be used for establishing connections at other link circuits. When the connection is completed vto telephone line E, the subscriber on'this line is rung-automatically in theusual manner at vthe automatic'exchange and when the subscriber on this line answers'the circuit is completed for conversation between the subscribers on lines A and E. In case the operatorhas not by then released key 5 conversation will take place over condensers 25 and 26 as shown through contacts of relay 23, for it will be remembered that in such a case relay 12 is still operated. the connection at the end of the conversation inthe usual manner employed in manual telephone exchange systems.

The diagram shown in F ig. 2 illustra-tes in simplified form the arrangement for the inclusion of resistance 21 in parallel with retardation coil 22, in the circuit for relay 10 and serves in connection with the curves shown in F ig. 3 to show how sufficient current is immediately supplied for relay 10 to maintain itenergized when contacts 24 are open. If line 30, Fig. 3, is considered as representing the value of the current passing through relay 10 when contacts 24 are closed and line 31 represents the value of the current at which the relay 10 will release its armature, line 32 may represent the value of current for relay 10 when contacts 23 are closed and contacts 24 are open.v

This later current which isv that passing through resistance 21 and retardation coil 22 in parallel is, therefore, sufficient to hold the relay 10 energized, until the current through retardation coil 22 is built up to such a value as represented by line 35 as to permit relay 10 to Ibe held when the resistance 21 is removed by the opening of contacts 23. If, on the other hand, resistance 21 was not included in this circuit at t-he'timel contacts`24 are open, the current through retardation coil 22 would build up approximately in accordance with the curve 33 .and relay 10 would therefore be permitted to release for a period equal to the Vdistance 34C and consequently disturb the connection established by the operation of this relay. It is evident then that therinclusion of resistance 21' in parallel with the' retardation coil 22 for a short interval will/at once establish the required circuit conditions for holding relay 10 energized and thus permit the inclusion of retardation coil 22 in this circuit between series of impulses or after the setting up operation is completed without disturbing the control circuit.

What is claimed is:

1. In a telephoney system, an impulse circuit,.an impulse sendertherefor, an impedance element in said circuit, means for shortcir-cuiting and impedance during a desired period, and means for including a resistance in parallel with said impedance element for a short interval after the shortcircuit has been removed.

2. In a telephone system, an impulse cir- `The operator may release i in cuit,y an impulse sender therefor, an impedance element 111 said circuit, means op- Y crated by the actuation of the sender for short-circuiting said impedance during a desired period, and means controlled by the sendervfor including a resistance in parallel With the impedance for a short interval after the short-circuit has been removed.

3. ln a telephone system, an impulse circuit, an impulse sender therefor, an impedance element normally in said circuit, a resistan ce element normally disconnected from said circuit, and means for short-circuiting said impedance during a desired period, and for including said resistance in parallel with said impedance for a short interval after the short-circuit has been removed.

ln a telephone system, an impulse circuit, an impulse sender therefor, an impedance element in said circuit, means operated by the actuation of the sender for shortcircuiting said impedance during a desired period, .and means operated by the actuation and'release of the sender for including a resistance element in parallel with the impedance element for a short interval after the release of the sender.

5. ln a telephone system, an impulse circuit, an impulse sender therefor, an impedance element in said circuit, a resistance element, mean-s responsive to the actuation of the sender for short-circuiting the impedance element during a desired period, and means comprising a relay arrangement controlled by the sender for including said resistance in parallel with the impedance for a short interval afterthe sender is released.

6. In a telephone system, an impulse circuit, an impulse sender therefor,tWo resistance elements, one of Which is included in said circuit While the sender is in normal position, and means for short-circuiting said elements ,While the impulse sender is in actuated position and for including the other resistance element in said impulse circuit for a short interval after said sender has returned to normal position.

7. ln a telephone system, an impulse circuit, an impulse sender therefor provided with impulse contacts and off-normal contacts, an impedance element in said circuit in series With the impulse contacts of the sender, a resistance element, a relay responsive to interruptions in the impulse circuit by said impulse contacts, means for shortcircuiting said impedance element controlled by said olf-normal contacts vvhen actuated, and means controlled by said olf-normal contacts when actnatedfor including said resistance element in parallel with said i111- pedance element a short interval after said olf-normal contacts are released in normal position to prevent the impulse responsive relay from deenergizing after the removal of the short-circuit by said release of the the off-normal contacts.

8. ln a telephone system, an impulse circuit, an impulse sender therefor, an iinpedancerelement in said circuit, a resistance, meansl for short-circuiting said impedance element during ay desired period, means for including the resistance in parallel with said impedance element a short interval after the short-circuit has been removed, and means for normally short-circuiting the impulse contacts of the sender and for removing said sliort-circuit during the operation of the sender.

. 9. In a telephone system, an impulse circuit, an impulse sender therefor, an impedance element in said circuit, a resistance, means for short-circuiting said impedance element during a desired period, means for including the resistance in parallel with said impedance element a short interval after the short circuit has been removed, and means controlledby the sender for normally short-V circuiting the impulse contacts of the sender and for removing said short circuit While the sender is actuated.

l0. ln a telephone system, calling and called subscribers lines, an operators telephone set adapted to be connected With said calling subscribers line, an impulse circuit normally connected to said telephone set, an automatic switch, an impulse sendei' in said circuit, an impulse responsive relay in said impulsecircuit for the operation of said switch to connect the impulse circuit with a Wanted subscribers line, means for disconnecting said calling's'ubscribeNs line and operators telephone set from said i111- pulse circuit While the impulse sender is operated, an impedance element normally shunted across the conductors of said impulse circuit, a resistance, and means for short-circuiting said impedance during the operation of the sender and for including the resistance in parallel with the impedance in said impulse circuit a short interval after the sender is released.

ll. In Aa telephone system, calling and called subscribers lines, an operators telcphone set adapted to be connected with said calling subscribers line, an impulse circuit normally connected to said telephone set, an automatic switch, an impulse sender in said circuit, a trunk circuit adapted to be connected to said impulse circuit and an impulse responsive relay in said trunk circuit for the operation of said switch to connect the trunk circuit 'to a Wanted subscribers line, means for disconnecting said calling subscribers line and operators telephone set from said impulse circuit While the impulse sender is operated, an impedance element normally shunted across the conductors of said impulse circuit, a resistance, and means for short-circuiting said impedance during the operation of the sender and for including the resistance in parallel With the impedance in said impul'se circuit a short interval after the sender is released.

12. In a telephone system, a telephone line, an operators telephone set adapted to be connected thereto, an impulse circuit connected to said operators telephone set, an impedance element bridged across the conductors of said impulse circuit, a resistance, an impulse sender in said impulse circuit, means controlled by the operation of said sender for short-circuiting said impedance, for disconnecting the telephone line and operators set from the impulse circuitduring the operation of the sender and for including the resistance in parallel With the impedance for a short interval after the releas of the sender.

13. In a telephone system, telephone lines, an operators telephone set adapted to be connected to one of said lines, an impulse circuit, a trunk circuit, an automatic switch, an impulse responsive relay for the control of said 'switch to connect to another of said lines, an impulse sender having impulse contacts in said impulse circuit, an impedance element across the conductors of said impulse circuit, a resistance element, and means under control of saidl'sender for disconnecting the operators telephone set Jfrom the impulse circuit, for short-circuiting the impedance element and connecting the impulse circuit to the trunk circuit While the sender is in operated position, and for in oluding the resistance in parallel With the impedance for a short interval after the return of the sender to normal.

14. In a telephone system, an impulse circuit, an impulse sender having impulse contacts in said impulse circuit, an impedance element in said circuit, a resistance element, means controlled by the sender operations for opening a short-circuit in said impulse circuit across the impulse contacts for closing a short-circuit for the impedance across the conductors of the impulse circuit While the sender is in operated position and for including the resistance in parallel With the impedance for a short interval after the sender has returned to normal.

15. In a telephone exchange system, an impulse circuit, an impedance element in said circuit, an impulse sending device having its impulse contacts in said circuit, an impulse responsive relay in said circuit, means responsive to the actuation of the sender for removing 'the impedance element. from said circuit and for closing a direct path for said impulse contacts to said impulse responsive relay, a resistance element, means under control otl the sender for including for a short interval after the return of the 'sender to normal the resistance element in parallel With the impedance elements to provide a loW impedance path for maintaining the impulse responsive relay operated after the direct path has been removed due to the release of the sender.

16. In a telephone system, a relay in series With an impedance, said impedance being of a value insufficient to cause the immediate energization of said relay but suticient to maintain said relay energized after its energization, means for short circuiting said impedance, and means for shunting said impedance temporarily incident to the removal of Isaid short-circuit by said iirst means.

17. In a telephone system, a relay in series with an impedance, said impedance being oit' such a value that it Will not alone permit the immediate energization of said relay therethrough but will hold it if once energized, means for short-circuiting said impedance to permit the relay to be energized, and means for shunting said impedance for a short interval after the short circuit has been removed to allow lsaid relay to be maintained energized through said impedance alone.

18. In a telephone system, a relay in series With an impedance, said impedance being of such a value that it Will not alone permit the immediate energization of said relay therethrough but Will hold it ifV once energized, means for short-circuiting said impedance to permit the relay to be energized, and means for shunting said impedance for an interval of time after the short circuit has been removed to permit the cur rent therethrough to increase to such an extent as to hold the relay energized.

In Witness whereof, I hereunto subscribe my name this 5th day of December A. D., 1923.

JAMES B. NEWSUM. 

